typeof foo === 'strnig'
'strnig' === typeof foo
if (typeof bar === 'umdefined') {}
typeof foo !== 'strnig'
'strnig' !== typeof foo
if (typeof bar !== 'umdefined') {}
typeof foo != 'strnig'
'strnig' != typeof foo
if (typeof bar != 'umdefined') {}
typeof foo == 'strnig'
'strnig' == typeof foo
if (typeof bar == 'umdefined') {}
if (typeof bar === `umdefined`) {}
if (typeof bar !== undefined) {}
typeof foo === "strnig"
typeof foo == "undefimed"
typeof bar != "nunber"
typeof bar !== "fucntion"